/Engine/Source/Runtime/Core/Public/Experimental/Async/AwaitableTask.h
Await the Task Completion and get the result, this will assert if this is a Dummy Handle. Awaiting an initizialized but not launched task will run ('launch') it synchronously in the current thread. use BusyWaitUntilLaunched if you want to wait for launching the task on another thread.
ReturnType Await()